JP2007010121A - Backing plate structure for drum brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backing plate structure capable of miniaturizing a drum brake and reducing the weight and the manufacturing cost. <P>SOLUTION: A collar part 56 is integrally formed on a backing plate 50 by ironing and spinning, and thereby compared to the case where a separately manufactured collar is welded, a number of parts can be reduced, and welding for attaching can be dispensed with, and therefore, the processing cost can be lowered, and miniaturization and reduction of the weight can be achieved. Further, compared to the case where the collar is formed by bending an outer peripheral end of the backing plate, position and shape accuracy equivalent to or higher than it can be maintained, and a thickness dimension of the collar part 56 can be made to be thinner than a thickness of the backing plate 50. Therefore, miniaturization and reduction of the weight of the drum brake can be achieved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drum brake backing plate structure.

  A metal main body, an annular flange formed on one side of the outer peripheral edge thereof, and an annular collar projecting on the one side on the inner circumference side by a predetermined distance from the flange. There is known a backing plate structure of a drum brake provided with (see, for example, Patent Documents 1 to 3). The collar is for constituting a labyrinth seal by being fitted with play in an annular groove formed in an annular end surface of the rotary drum.

  FIG. 1 is a front view showing a drum brake provided with the backing plate 10 as described above, and FIG. 2 is a cross-sectional view taken along line AA thereof. 1 and 2, a pair of brake shoes 12 and 14 having a substantially arc shape are provided on one surface of a backing plate 10 fixed to a vehicle body side member rotatably supporting a wheel. 16 and 18 are provided so as to be able to expand each other. The brake shoes 12 and 14 correspond to friction members, a shoe web 20 positioned substantially parallel to the plate surface of the backing plate 10, a shoe rim 22 fixed to the outer peripheral side edge of the shoe web 20, and the shoe rim And a lining 24 fixed to the outer peripheral surface of each of them.

  One end portions of the pair of brake shoes 12 and 14 are respectively engaged with both end portions of the brake actuator 26 disposed on the backing plate 10, and are separated by the brake actuator 26 when braking the service brake. It is expanded and pressed by the rotating drum 28 that rotates together with the wheels to generate a braking force. A return spring 30 is stretched across the brake shoes 12, 14 at a position near the brake actuator 26 and on the inner peripheral side of the backing plate 10, and is urged toward each other. A strut 32 is disposed alongside the return spring 30 to define the approach position of the pair of brake shoes 12 and 14 that are brought into close proximity according to the urging force of the return spring 30 during non-braking. The other ends of the brake shoes 12 and 14 are in contact with anchors 34 fixed to the backing plate 10. Reference numeral 36 denotes a tension coil spring for pressing the strut 32 against the brake shoe 12, reference numeral 38 denotes a tension coil spring for pressing the brake shoes 12 and 14 against the anchor 34, and reference numeral 40 denotes a shoe gap automatic adjusting mechanism.

  The backing plate 10 includes a flange portion 42 formed by bending the outer peripheral edge to one surface side by press working or the like. The flange portion 42 has a cylindrical shape that is substantially perpendicular to the plate surface of the backing plate 10. Further, an annular collar 44 having an L-shaped cross section is attached to the inner peripheral side of the flange portion 42 by spot welding or the like. The collar 44 has a slightly lower height than the flange portion 42 and is located slightly away from the flange portion 42 toward the inner peripheral side. Therefore, an annular groove is formed between the flange portion 42 and the collar 44. Further, the collar 44 is provided with a cut 46 at the lower end position in FIG. The cut 46 constitutes a drain hole for discharging water that has entered the drum brake.

Further, an annular groove 48 is provided on the annular outer peripheral end surface of the rotary drum 28 toward the backing plate 10, and the tip of the collar 44 is fitted into the annular groove 48 with play. It has been. The groove width dimension of the annular groove 48 is sufficiently larger than the thickness dimension (diameter width dimension) of the collar 44, and the width dimension of the annular groove between the flange portion 42 and the collar 44 is also the rotating drum 48. Which are sufficiently larger than the thickness dimension of the portion located between them, and they are not in contact with each other. Therefore, when assembled with the rotary drum 28, the drum brake is formed with a space bent from the outer peripheral edge to the inner peripheral portion by the flange portion 42, the collar 44, and the annular groove 48 to form a labyrinth seal. Therefore, water and dust are prevented from entering the drum brake while allowing rotation of the rotary drum 48.
Japanese Utility Model Sho 53-45383 Japanese Patent Laid-Open No. 06-002720 JP-A-11-230207

  By the way, in the backing plate structure shown in FIGS. 1 and 2, the L-shaped collar 44 needs to be manufactured separately from the backing plate 10 and welded to a predetermined position. For this reason, the number of parts increases and the manufacturing process of the drum brake becomes complicated, which hinders weight reduction and cost reduction. In addition, since it is difficult to ensure the dimensional accuracy, shape accuracy, and mounting position accuracy of the collar 44, there is a disadvantage that the manufacturing yield is lowered due to these errors. If the tolerance is increased, the space formed by the flange portion 42, the collar 44, and the annular groove 48 is increased, so that the waterproof / dustproof ability of the labyrinth seal is impaired.

  On the other hand, in Patent Document 2, it is proposed that the backing plate 10 is bent by a press to integrally form the flange portion and the collar. According to this structure, it is not necessary to prepare and weld a collar separately, and since the collar is formed with high relative positional accuracy with respect to the flange portion, the flange portion, the collar, In addition, the bending space of the labyrinth seal formed by the annular groove is sufficiently narrowed to obtain a high waterproof / dustproof capability. However, in such a bending process, the thickness dimension of the collar becomes twice or more the thickness dimension of the backing plate 10. Therefore, it is necessary to increase the groove width of the annular groove 48 of the rotary drum 28 as compared with the conventional one, which hinders the reduction in size and weight of the drum brake.

  In Patent Document 3, a dust cover made of synthetic resin is attached to the outer peripheral side instead of welding the collar 44 to the inner peripheral side, but such a structure is also disclosed in Patent Document 1. There are similar problems with the structure.

  The present invention has been made against the background described above, and an object of the present invention is to provide a backing plate structure that can further reduce the size and weight of the drum brake and can be manufactured at a low cost.

  In order to achieve such an object, the gist of the present invention is that a metal main body part, an annular flange part formed on the outer peripheral edge part thereof by bending on one surface side, and a predetermined part than the flange part. An annular collar projecting on one surface on the inner circumferential side by a distance, and a labyrinth seal is configured by fitting the collar with play in an annular groove formed on the annular end surface of the rotating drum. A drum brake backing plate structure, wherein (a) the collar is formed integrally with the main body by ironing.

  In this way, since the collar is integrally formed on the backing plate by ironing, the number of parts is reduced and welding for mounting is unnecessary compared to the case where the collar is a separate part. Therefore, the processing cost is reduced, and further reduction in size and weight is possible. In addition, compared with the case where the collar is formed by bending the outer peripheral edge of the backing plate, the collar thickness dimension is equal to or greater than the backing plate thickness while maintaining the same or better position and shape accuracy. In addition, since the thickness can be freely set to an appropriate thickness dimension, there is an advantage that the drum brake can be further reduced in size and weight.

  The “predetermined distance”, that is, the distance between the flange portion and the collar in the radial direction is such that the collar can be fitted into the annular groove of the rotating drum with play. That is, it is set to a size sufficiently larger than the radial thickness dimension of the outer peripheral side portion of the annular end surface of the rotating drum.

  Here, preferably, the backing plate structure is formed by providing a recess projecting to the back side opposite to the one side in a part of the formation position of the collar of the main body, and performing the ironing process. A through-hole formed in the recess is provided so as to penetrate the collar base in the radial direction. In this way, when ironing is performed on the recess provided at the collar forming position, the through-hole penetrating in the radial direction of the backing plate has a size corresponding to the size of the recess. Formed at the base of For this reason, the through hole functions as a drain hole from the inside of the drum brake, so that when the collar is welded, the drain hole is easily formed as in the conventional case where a gap functioning as a drain hole is formed at the seam. Can be formed.

  Preferably, the recess is provided continuously on the outer peripheral side of the outer peripheral edge of the anchor fixing portion formed so as to protrude to the one surface side of the backing plate. The anchor fixing portion is for fixing an anchor that receives one end of a pair of brake shoes on one surface of the backing plate. In this way, like the conventional general backing plate structure, There are advantages that a drain hole is formed in the vicinity and that the drain hole can be provided only by a slight shape change of the press working die.

  Preferably, the ironing is ironing spinning from the outer peripheral side to the inner peripheral side of the backing plate. That is, the plate member for constituting the backing plate is rotated around the rotation axis perpendicular to the plate surface, while the roll is pressed in the plate thickness direction of the plate member and sent to the inner peripheral side in the radial direction. The collar is molded while causing a thickness reduction. In this way, a collar is formed using the material of the flange portion. Although the flange portion does not require strength as compared with the main body portion, the flange portion formed by bending has conventionally had excessive strength with the same plate thickness as the main body portion. According to the above aspect of the present invention, since the plate thickness of the flange portion is reduced while keeping the main body portion the same as the conventional plate thickness, it is possible to further reduce the weight of the backing plate while ensuring the necessary strength of the main body portion and the flange portion. Can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 3A is a view showing a cross section of the backing plate 50 according to one embodiment of the present invention, and corresponds to the view in which other components are removed from FIG. Since parts other than the backing plate 50 in the configuration of the drum brake are configured in the same manner as the conventional one shown in FIGS. 1 and 2, only the configuration of the backing plate 50 will be described below.

  The backing plate 50 is entirely made of a single metal plate, for example, an iron plate. The backing plate 50 includes a disk-shaped main body portion 52, an annular flange portion 54 formed by bending the outer peripheral edge portion thereof on the left side or one surface side in FIG. 3A, and the inner periphery of the flange portion 54. And an annular collar portion 56 projecting on one side thereof.

  The collar portion 56 has a slightly lower height than the flange portion 54 and is disposed slightly spaced from the flange portion 54 toward the inner peripheral side. These height dimensions and the distance from the flange portion 54 are determined so as to form a labyrinth seal by fitting with the outer peripheral end portion of the rotating drum 28 on the backing plate side shown in FIG. is there. However, the collar portion 56 may be configured to have a height dimension higher than that of the flange portion 54 as long as there is no hindrance in forming the labyrinth seal.

  Further, as shown in FIG. 3B in which the portion B in FIG. 3A is enlarged, the collar portion 56 is formed integrally with the main body portion 52. In the main body 52, the thickness dimension of the inner peripheral portion 52a of the collar portion 56 is configured to be thicker than the outer peripheral portion 52b. Further, the flange portion 54 following the outer peripheral portion 52b has the same thickness as the outer peripheral portion 52b. Moreover, the thickness dimension of the collar part 56 is still thinner than the said outer peripheral side part 52b, for example, is about 1/3 to 1/2 of the thick inner peripheral side part 52a. In addition, an anchor mounting portion 58 for fixing the anchor 34 is formed in the vicinity of the lower end portion of the main body 52 so as to protrude to the left in FIG. 3A, and the collar portion 56 includes the anchor mounting portion. It is located on the outer peripheral side from 58.

  The collar portion 56 configured as described above is formed by, for example, ironing spinning. 4A and 4B are views for explaining a method of forming the collar portion 56. FIG. In FIG. 4A, a plate material 60 for constituting the backing plate 50 is formed by pressing a single iron plate. That is, by pressing, an axle hole 62 through which an axle or the like is passed, an attachment hole 64 to which the brake actuator 26 is attached, the anchor attachment portion 58 and the like are provided on the iron plate.

  The collar portion 56 is manufactured, for example, by subjecting the plate material 60 to a squeezing and spinning process. That is, by rotating the plate material 60 about a rotation axis perpendicular to the plate surface and pressing the squeezing tool against the one surface 66, the squeezing tool is sent in the direction of arrow S on the inner peripheral side of the plate material 60. A collar portion 56 is formed. At this time, since the plate thickness of the plate material 60 is reduced by the squeezing tool, the outer peripheral side portion 52b is thinner than the inner peripheral side portion 52a as described above. FIG. 4B shows the plate material 60 ′ after the collar portion 56 is formed. The collar portion 56 can have any thickness dimension by appropriately changing the spinning processing conditions such as the pressing strength and feed rate of the squeezing processing tool, but in this embodiment, it is thinner than the outer peripheral portion 52b. The processing conditions are defined as follows.

  The backing plate 50 of this embodiment is manufactured by bending the flange portion 54 on the plate member 60 ′ having the collar portion 56 formed as described above. The bending of the flange portion 54 can be performed by pressing or drawing spinning.

  Therefore, according to the present embodiment, since the collar portion 56 is integrally formed with the backing plate 50 by ironing spinning, the number of parts is reduced as compared with the case where a separately manufactured collar is welded. Since welding for mounting is unnecessary, the processing cost is reduced, and further reduction in size and weight is possible. Moreover, the thickness dimension of the collar portion 56 is made larger than the thickness of the backing plate 50 while maintaining the position and shape accuracy equal to or higher than when the collar is formed by bending the outer peripheral edge portion of the backing plate. Can also be thinned. Therefore, there is an advantage that the drum brake can be reduced in size and weight.

  Further, according to the present embodiment, the collar portion 56 is formed using the material of the flange portion 54 by ironing spinning, so that the flange portion 54 is kept in the same thickness as that of the conventional body. The plate thickness is reduced. Therefore, the backing plate 10 can be further reduced in weight while ensuring the necessary strength of the main body 52 and the flange 54.

  FIG. 5 is an enlarged view showing the vicinity of an anchor mounting portion 72 of a plate member 70 which is an intermediate part for manufacturing a backing plate according to another embodiment of the present invention. FIG. 5A corresponds to FIG. A front view and (b) are the CC sectional views. In the present embodiment, a recess 74 is provided from the part of the lower edge of the anchor mounting portion 72 in FIG. 5A to the outer peripheral side thereof. As shown in FIG. 5B, the recess 74 is located at the bottom of the anchor mounting portion 72 that is convexly formed on the one surface side of the plate material 70, and is slightly recessed on the back surface side than the one surface 78 of the plate material. It is out. The recess 74 is formed at the same time when the anchor mounting portion 72 is formed by press working. That is, it is provided by changing the shape of the mold for forming the anchor mounting portion 72 from the conventional one.

  FIG. 6 is a diagram showing a plate material 70 ′ in which a collar portion 76 is protruded from the outer peripheral side of the anchor mounting portion 72 by subjecting the plate material 70 to iron spinning, and (a) and a DD thereof. (B) which is a view section corresponds to FIGS. 5 (a) and 5 (b), respectively. The recess 74 is provided at a position where the collar portion 76 is formed (that is, on the circumference where the collar portion 76 is formed) so as to intersect with this. For this reason, when the collar portion 76 is formed by ironing spinning, one surface 78 of the plate member 70 is not scraped off on the recess 74, so that a through-hole 80 penetrating in the radial direction is recessed in the base portion of the collar portion 76. 74. This through-hole 80 functions as a drain hole as in the cut 46 provided in the conventional collar 44 shown in FIG.

  That is, when the collar portion 76 is formed by iron spinning as in this embodiment, the cut 46 cannot be formed as in the case of welding, but a mold for forming the anchor attachment portion 72 as described above. By forming the recess 74 with a slight change in shape, it is possible to provide the through hole 80 that functions as a drainage hole at the same time as the collar portion 76 is formed. The size of the through hole 80 can be freely changed by appropriately determining the size and shape of the recess 74.

  In addition, the recess 74 for forming the through hole 80 is formed integrally with the anchor mounting portion 72 as described above, and if it is a position that intersects the collar 76, it does not affect the operation of the brake. Thus, the plate material 70 can be formed at an appropriate position.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a front view which shows the structure of the drum brake provided with the conventional backing plate. It is AA sectional view taken on the line in FIG. (a) is a figure which shows the cross section corresponding to FIG. 2 in the backing plate of this invention, (b) is a figure which expands and shows the B section in (a). 4A and 4B are cross-sectional views corresponding to FIG. 3A for explaining the manufacturing method of the backing plate of FIG. 3, wherein FIG. 3A shows a state after press working, and FIG. 3B shows a state after color formation. FIG. It is a figure which shows the anchor attachment position vicinity after the squeezing process for demonstrating the manufacturing method of the backing plate of the other Example of this invention, Comprising: (a) is a front view, (b) is C- of (a). It is C sectional view. (a) and (b) are the front views and DD sectional views corresponding to Drawing 5 (a) and (b) after ironing processing, respectively.

Explanation of symbols

50: backing plate, 52: main body, 54: flange, 56: collar

Claims (2)

A metal main body, an annular flange formed on one side of the outer peripheral edge thereof, and an annular collar projecting on the one side on the inner circumference side by a predetermined distance from the flange. A drum brake backing plate structure for forming a labyrinth seal by fitting the collar with play in an annular groove formed on the annular end surface of the rotating drum,
A drum brake backing plate structure, wherein the collar is integrally formed with the main body by ironing. A recess projecting to the back side opposite to the one surface is provided in a part of the collar forming position of the main body portion, and the concave portion is formed so as to penetrate the base portion of the collar in the radial direction by performing the ironing process. The drum brake backing plate structure according to claim 1, further comprising a through hole formed on the surface.

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